On August 21, 1879, in a poor and remote village in Mayo, about a dozen people saw a bright light outside the gable of the local Catholic church and within it figures of the Virgin Mary, St Joseph and St John. The apparition persisted for several hours, though the life-size figures neither spoke nor moved.

A subsequent investigation by a panel of priests concluded that testimony given by local people about the apparition was acceptable, and nowadays Knock is one of the leading Marian shrines in the world, drawing about 1.5m visitors a year.

While social scientists are in no position to decide whether supernatural persons visit this world, claims of such sightings have been given different levels of credence depending on place and time.

Apparitions are really stories with messages, and what I am suggesting is that the Knock apparition of 1879 was linked to local criticism of the way priests were carrying out their duties. Many historians say the Penal Laws oppressed Catholics and reduced priests to fugitives. After these laws were removed, Catholics were able openly to support priests. The clergy slowly moved people away from semi-pagan superstitions and turned them into Mass-attending parishioners.

Even still, Catholics were careful not to antagonise the fairies, and regularly made pilgrimages to local outdoor sites with no connection to the church. Lay people also resisted clergymen who abused their roles — there had been a strike in Knock protesting at the money priests were asking for sacramental services.

People told stories about priests who went too far in condemning fairy healers and found their horses stuck to the ground. Others related how, when lazy priests were slow to do their duty, the Virgin herself attended the dying. In popular stories, heaven often spoke against sinful clergymen. Apparitions were seen as a weapon of the weak against their oppressors.

The events of the Land War provoked a clerical authority crisis in Knock, because the local priests supported landowners over the tenants. One priest, Fr Cavanagh, denounced local leaders of the agitation from the altar, and this prompted a huge “indignation meeting” against him in June 1879. Just a few months later the Virgin appeared outside the chapel along with other personages and figures, a bishop prominent among them.

Published accounts of the apparition were filtered through the local priests, including Cavanagh. These are now the only sources for what is “known” and accepted about the episode.

While precipitated by a crisis in clerical authority, the apparition was publicised in a very different fashion. Reports omit any reference to local confrontations over clerical authority and to traditional local religiosity, with its built-in ways of holding priests and bishops to proper standards of behaviour.

The local priests, Frs Cavanagh and Bourke, successfully monopolised presentation of the apparition in the wider media. Practically all the early news reporters relied on the co-operation of these priests and interviewed people they selected. What was left out of the press reports — and what reporters were incapable of discovering due to their ignorance of the Irish language — was the traditional idiom of Virgin appearances as commentary on the role of priests.

The promoters never mentioned the overt challenges to the priests around the time of the apparition. They did not mention, for example, the demonstration against Cavanagh in June or the damaging of Bourke’s crops and fences or the way he had been vilified in the Connaught Telegraph in June and July.

The apparition scene at Knock was probably influenced by some seers’ recall (probably unconscious) of a scene depicted in the new stained-glass window in a church in Ballyhaunis. But the seers endowed the Virgin with a crown that she did not wear in the original. This crown incontrovertibly constituted her as a figure of authority.

For frustrated faithful, an apparition could prove whose “side” the divine arbiters of right and wrong were on. Sometimes it carried a “could do better” message for clergy. The people believed the Virgin Mary was on their side and not on the hierarchy’s.

Similar detailed studies of the local context might well find that other Marian apparitions also had different origins from those widely believed later.

Eugene Hynes is Associate Professor of Sociology at Kettering University, Michigan and author of Knock: The Virgin’s Apparition in Nineteenth Century Ireland (Cork University Press)

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